Rotor for a wind-driven generator

ABSTRACT

The present invention refers to a rotor for a fluid-kinetic machine comprising a rotatably supported hub, the support being provided with axial bearing means, an outer ring which is indirectly supported on said hub, and rotor blades which are arranged in an area between said hub and said outer ring. In order to provide a possibility of utilizing the influence of the gyroscopic effects, which occur during operation of the rotor, for the purpose of stabilizing the rotor, it is suggested in accordance with the invention that the outer ring should be composed of a plurality of arcuate sections in the circumferential direction and should be arranged essentially in the plane of rotation of the axial bearing means, and that the arcuate sections of the outer ring should be under the action of flexible tension elements which embrace said arcuate sections at least partly and which are secured to a carrier ring.

DESCRIPTION

A known rotor for a wind-driven generator, which comprises a rotatablysupported hub and in the case of which the support is provided withaxial bearing means, is equipped with an outer ring, which is indirectlysupported on said hub, and with rotor blades which are arranged in anarea between said hub and said outer ring. In order to guaranteeeconomical operation in the case of wind-driven generators provided withsuch a rotor, it is necessary to construct the rotor such that it hassuitably large dimensions. In particular with regard to alternativepossibilities of energy generation, a great variety of structuraldesigns of such rotors has already been suggested and tested underpractical conditions. A disadvantage which is common to the hithertoknown rotors primarily is to be seen in the fact that said rotors have avery large mass because of the required mechanical strength. Due to thegyroscopic effects produced, this large mass subjects the bearings to anexcessive load, and, in spite of detailed calculations, it is verydifficult to estimate said load in advance. This had the effect thatmany tests with big wind systems failed. An additional problem arisingin the case of such rotors is the lack of balance of the rotatingcomponents. In particular in the case of big rotors it is practicallyimpossible to balance these rotors before they are installed in the windpower station in question. Due to the size of the rotor and the manifoldinfluence and interference factors, it is practically impossible tobalance the rotor when it has been installed. Hence, known rotors aremarkedly unstable in the case of higher speeds so that, e.g. at higherwind speeds, the rotor of a wind power station must be stopped.

U.S. Pat. No. 36 95 780 discloses a rotor, which is to be used for ahelicopter or for a similar vehicle. The rotor is provided with an outerring, which is indirectly supported on a hub and which is arrangedcoaxially with said hub. Several rotor blades are arranged in theintermediate area between the outer ring and the hub. The outer ring isconnected to the hub by means of a plurality of tension spokes. The hubis secured to the end of a driven shaft. In the case of this rotor, too,higher rotational speeds will have the effect that gyroscopic forces andmoments will occur, and it is very complicated, if not impossible atall, to govern these forces and moments. A point which turns out to beparticularly disadvantageous is the projecting mode of supporting therotor at the end of the rotatable shaft. This causes additional momentswhich result in a precession of the gyroscope defined by the rotor.

Swiss Pat. No. 437 924 discloses a ring turbine blower provided with ablade carrier which is arranged axially with regard to a hub and whichsurrounds said hub. The blade carrier is connected to the hub by meansof several spokes. The overall arrangement of the spokes, of the hub andof the blade carrier corresponds to the arrangement known from abicycle. In this connection, it must be specially mentioned that theblade carrier is designed as an integral part in the form of a solidring. Furthermore, the spokes are not flexible, but are made of ahigh-strength material, such as steel or piano wire, and, consequently,they do not have any flexible properties whatsoever.

U.S. Pat. No. 2 855 179 discloses a turbine provided with an annularstrip which is arranged coaxially with a hub. The strip is supported onthe hub by means of spokes. Also in the case of the turbine known fromthis publication, the strip consists of a closed, integrally formedring. A plurality of rotor blades is arranged between the hub and thestrip, said rotor blades being fastened to the turbine, i.e. inparticular to the strip. The fastening is effected in such a way thatthe spoke associated with each rotor blade penetrates said rotor blade,embraces the strip and is guided back to the hub through the same rotorblade. It follows that each of the spokes defines a single loopconstituting a closed loop with regard to the rotor blade and the strip.In addition, the turbine is provided with an inner strip, which isintegrally formed as well and which abuts on the radially inner ends ofthe rotor blades. The inner strip forms an elastic support means in thiscase and, consequently, it does not serve to fasten the rotor blades.

In comparison with this prior art, the invention is based on the task ofproviding a rotor of the type disclosed in the generic clause of claim1, which has a simple, light and stable structural design and whichpermits such a mode of support that the gyroscopic effects occurring canbe used for stabilizing the position of the rotor.

In accordance with the invention, this task is solved by means of thecharacterizing features of claim 1 in the case of a rotor according tothe generic clause.

The rotor according to the invention which is used for a fluid-kineticmachine is characterized by substantial advantages. The outer ring iscomposed of a plurality of arcuate sections in the circumferentialdirection; in this connection, the term arcuate sections need not beunderstood in a material sense. The outer ring can, however, besubdivided into several ideal arcuate sections. Due to the fact that theouter ring is arranged essentially in the plane of rotation of the axialbearing means, the gyroscopic effects occurring can be transferred in anoptimum manner to the rotating axle or the rotating shaft and,consequently, to the suspension of the rotor. Additional bending momentsor additional moments which might result in an uncontrolled precessionof the rotor can be avoided in this manner. Another substantialadvantage of the rotor according to the invention is to be seen in thefact that the arcuate sections of the outer ring are under the action offlexible tension elements, which embrace said arcuate sections at leastpartly and which are secured to a carrier ring. It is thus possible thateven a rotor having a very large diameter is supported on the hub insuch a way that a lack of balance is compensated while the rotor isrunning so that said rotor is self-balancing and guarantees a smooth andperfect operation, consequently. It follows that the load on thebearings is reduced to a minimum. The fact that the outer ring or ratherits arcuate sections are under the action of tension elementsadditionally leads to a very stable overall structural design of therotor, since the arcuate sections are, at least partly, embraced by theflexible tension elements and since, consequently, the centrifugalforces occurring can be dissipated via the flexible tension elementsinto the carrier ring.

A particularly advantageous structural design of the rotor is based onthe features that the carrier ring is formed integrally with the hub andthat the outer ring is supported on said hub by means of a plurality ofpressure elements and flexible tension elements, and that, in the areawhere the respective pressure element is fastened, each flexible tensionelement is deflected in the circumferential direction on the outer ringand is secured to one of the arcuate sections of the outer ring whichconstitute the neighbouring arcuate sections in said circumferentialdirection. Due to this structural design, it is possible to constructthe rotor in a very simple manner by using standardized components whichare available on the market. Furthermore, the rotor is characterized bya very low total weight. Due to the fact that the carrier ring and thehub are formed integrally with each other, the highest possible strengthof the whole construction is guaranteed. The use of pressure elementsand tension elements offers the possibility of dimensioning theseelements in a particularly weightsaving manner and, in particular, alsothe possibility of fastening said elements to the hub and to the outerring in an extraordinary simple manner. Due to the fact that therespective flexible tension element is deflected and due to the factthat said tension element is fastened to a neighbouring arcuate sectionof the outer ring, the strength of said outer ring is additionallyincreased, without there being any necessity of designing said outerring itself with higher strength.

Another advantageous embodiment is based on the feature that fasteningof the respective tension element is effected in the deflection area ofthe neighbouring arcuate section of the outer ring or on the featurethat fastening of the respective tension element is effected in thedeflection area of the arcuate section of the outer ring following saidrespective neighbouring arcuate section. Depending on the dimensions ofthe rotor and its outer ring, it may prove advantageous to effectfastening of the respective tension element in one of the twoabovementioned manners. The fact that a further arcuate section of theouter ring is additionally embraced can result in a further increase ofthe overall stability and the balancing operation, which takes placeautomatically, can thus be additionally improved.

An inner ring which is composed of arcuate sections and arrangedcoaxially with the outer ring and between which the rotor blades arearranged can prove to be advantageous as well. In this case, the rotorblades are not arranged such that they extend up to and into the area ofthe hub so that the support of the rotor remains freely accessible.

Furthermore, a particularly advantageous embodiment of the rotoraccording to the invention is based on the features that the carrierring is formed by an inner ring which is arranged coaxially with theouter ring and which consists of a plurality of arcuate sections, thatthe rotor blades are arranged between the outer ring and the inner ring,that the inner ring is supported on the hub by means of a plurality ofpressure elements and flexible tension elements and that the individualarcuate sections of the outer ring and of the inner ring areinterconnected by means of a plurality of flexible tension elements. Inthe case of such a structural design, the outer ring, the rotor bladesas well as the carrier ring, which is formed by the inner ring, definean inherently stable structure, which, in addition to the advantageswhich have already been described hereinbefore, shows the furtheradvantage that the weight of the rotor can be reduced even more. Inaddition, it is possible to prefabricate the rotor independently of thehub and to support it on the hub by means of the pressure elements andthe tension elements only when it has arrived at the place ofinstallation.

Due to the fact that the respective flexible tension element is securedto the outer circumference of an arcuate section of the outer ring andto the inner circumference of an arcuate section of the inner ring, thearcuate sections in question are almost fully embraced. The stability ofthe overall system is this substantially increased once more.

Another feature which proves to be advantageous is that the pressureelement and the tension element are, in their respective radially outerareas, supported on a carrier which is adapted to be brought intoengagement with the inner ring. It is thus possible to prefabricate notonly the main part of the rotor consisting of the outer ring and of theinner ring, but also the bearing arrangement, which is positioned on theside of the hub and which consists of pressure elements and of tensionelements. The final assembly of the rotor is thus substantiallysimplified. An advantageous embodiment of the rotor according to theinvention is additionally provided by the feature that a respectivepressure element and a respective flexible tension element are arrangedaxially with regard to each other and in an axially displacedrelationship with regard to the plane of rotation of the outer ring. Itis thus possible to arrange the rotor in the plane of rotation of theaxial bearing means, whereas the fastening elements of said rotor arelocated in an area outside of said axial bearing means so that, on theone hand, said axial bearing means is accessible at any time and, on theother hand, it can be incorporated into a carrier construction for therotor in a suitable manner.

It also turns out to be advantageous that there is provided a respectivesecond flexible tension element which is arranged axially with regard tothe pressure element and in opposite relationship with the first tensionelement. Such a mode of supporting the outer ring and/or the inner ringon the hub guarantees even greater stability and strength in the axialdirection. Furthermore, the dimensions of the flexible tension elementscan be reduced, and this can result in a further reduction of weight.

In the following, the invention will be described on the basis ofembodiments in connection with the drawing, in which:

FIG. 1 shows a side view, part of which is a sectional view, of part ofa first embodiment,

FIG. 2 shows a partial side view of the side located on the right inFIG. 1,

FIG. 3 shows a top view of part of the outer circumferential surface ofthe rotor,

FIG. 4 shows a front view of a second embodiment, and

FIG. 5 shows a view, similar to that of FIG. 1, of the hub portion of anadditional embodiment.

FIG. 1 shows a side view, part of which is a sectional view, of a firstembodiment of the rotor according to the invention. For the sake ofclarity, the lower half, which is constructed symmetrically with theupper half, was omitted. The rotor is provided with a hub 1, which isconnected to a carrier in a suitable manner by means of radial bearingswhich are not shown in detail. If the rotor is used for a wind powerstation, it will be expedient to arrange the hub 1 in a horizontalposition. The hub 1 is provided with axial bearing means 2, which areonly schematically shown. If the rotor is used in a wind power station,the incoming air will be supplied, in accordance with FIG. 1, to therotor from the righthand side. The rotor is provided with an outer ring3 and an inner ring 9, which are arranged coaxially with each other andwith the hub 1 and which are supported essentially in the area ofrotation of the axial bearing means 2. The outer ring 3 and the innerring 9 are preferably constructed such that they define hollow channels,which are adapted to the respective mode of application in such a waythat optimum flow behaviour is guaranteed. The outer ring as well as theinner ring are preferably made of reinforced plastic material. Spacers12 are provided between the outer ring 3 and the inner ring 9, saidspacers guaranteeing the coaxial position of the two rings 3, 9 as wellas the distance at which they are arranged from each other. In the caseof the embodiment shown, the spacers 12 are inserted in appropriaterecesses of the outer ring 3 and of the inner ring 9. In addition, thespacers 12 are provided with central recesses through which flexibletension elements 7 and 14 can be passed. The tension elements 7 and 14extend through the spacers 12, and in the area of the inner ring 9 theyare deflected from their radial direction, which corresponds to theradial direction of the recess of the respective spacer 12, by means ofrespective deflection rollers 17, and then they are led towards the hub.The hub 1 is provided with two axially spaced deflection rollers 17, thetension elements 7, 14 being guided round said deflection rollers 17.The ends of the tension elements 7, 14 are secured to the centralportion of a pressure element 6. The pressure element 6 is supported onthe hub 1 as well as on the inner ring 9, preferably by means of a plugconnection 15. The area in which the pressure element 6 as well as thetwo tension elements 7 and 14 are attached and which is located at theside of the hub is laterally displaced from the plane of rotation of theaxial bearing means 2 when seen in the axial direction. As shown in FIG.2, the tension elements 7, 14 are deflected in the circumferentialdirection by means of a deflection roller 8 in the area of the outerring 3. The tension elements respectively embrace an arcuate section 5of the outer ring 3 and are secured either to the nearest deflectionroller 8 or, as shown in FIG. 3, to the deflection roller 8 coming aftersaid nearest one. The tension elements 7, 14 are pretensioned with theaid of tensioning means 16, which may, for example, be constructed as atension jack, so that the rotor has an appropriate stability. Due to thefact that the tension elements 7, 14 are pretensioned, a pressure isapplied to the pressure element 6 so that said pressure element remainsfixedly connected to the hub 1 and to the inner ring 9.

FIG. 2 shows a side view of the rotor ring side located on the right inFIG. 1. In the case of the embodiment shown, a rotor blade 4 isrespectively provided in the area of the spacers 12, the structuraldesign of said rotor blade 4 being not shown in detail. The shape of therotor blade 4 can be adapted to the desired conditions of use, e.g. tothe normally prevailing wind speed. The rotor blade 4 can either beattached to the spacers 12 or, in accordance with another possibility,said rotor blade 4 can be formed integrally with the spacers 12.

FIG. 3 shows a top view of the outer circumference of the outer ring 3,said figure showing, however, only part of the outer ring. As hasalready been described in connection with FIG. 1, the respectiveflexible tension elements 7, 14 are--after having passed the respectivespacer 12--deflected in circumferential direction round the deflectionroller 8. In the case of the embodiment shown, the end portion inquestion is fastened to the deflection roller 8 coming after the nearestdeflection roller, the flexible tension element 7, 14 being preferably awire rope whose end is bent to form a loop and is clamped by means of aclamping device which is not shown in detail. Fastening of the ends ofthe tension elements 7, 14 is preferably effected at a point inwards ofthe deflection area of the respective adjacent tension elements 7, 14 sothat an intersection of the tension elements is avoided.

FIG. 1 to 3 show an embodiment in the case of which there are providedone pressure element 6 and two tension elements 7, 14. It is, however,also possible to use only one tension element 7. However, in this casesaid one tension element 7 is preferably deflected and fastened in thecentral area of the deflection roller 8. If only one tension element 7is used, it will be sufficient to provide only one spacer 12 in thecentral area of which a recess is provided.

The hub 1 can be formed in one piece; it is, however, also possible tocombine said hub of several hub members which are arranged axially withrespect to one another. Also the fastening of the pressure element 6 canbe effected in many different ways, e.g. by means of additional clampingmembers.

FIG. 4 shows a front view of a second embodiment of the rotor accordingto the invention. In the case of this embodiment, the carrier ring isformed by the inner ring 9. The outer ring 3 and the inner ring 9 can bedesigned in the same way as in the case of the embodiment of FIG. 1-3.Several rotor blades 4 are again provided between the outer ring 3 andthe inner ring 9, said rotor blades being only schematically shown. Inthe case of the example shown, the rotor blades 4 simultaneously serveas spacers for guaranteeing a predetermined distance between the tworings 3, 9. The outer ring 3 as well as the inner ring 9 are composed ofseveral arcuate sections 5 of the outer ring and arcuate sections 11 ofthe inner ring, in which connection the term arcuate section is used inan ideal sense, but not in a material sense. The individual arcuatesections 5 of the outer ring 3 and the arcuate sections 11 of the innerring 9 are interconnected by means of a plurality of flexible tensionelements 10. As has already been described in connection with FIG. 1 to3, each arcuate section 5 of the outer ring is provided with adeflection roller 8 which has secured thereto an end of the respectivetension element 10. In the area of the outer circumference of the outerring 3, the tension element 10 is led to the neighbouring deflectionroller 8 and is deflected inwards round said deflection roller 8 in theradial direction and is then led to a deflection roller 18 of therespective arcuate section 11 of the inner ring. The tension element 10is also deflected round this deflection roller 18 in the circumferentialdirection and is secured to the neighbouring deflection roller 18 of theneighbouring arcuate section 11 of the inner ring. Hence, the respectivetension element 10 embraces one arcuate section 5 of the outer ring andone arcuate section 11 of the inner ring. For the purpose of tensioningthe respective tension element 10, a tensioning means 16 is provided.

In analogy with the embodiment according to FIG. 1 to 3, the hub 1 isprovided with several plug connections 15 having inserted thereinpressure elements 6 which are fixed in position by means of tensionelements 7, 14. The tension elements 7, 14 are each secured to a carrier13 which is connected to the radially outward end of the pressureelement 6. The carriers 13 are adapted to be brought into engagementwith the arcuate sections 11 of the inner ring in a manner which is notshown. Due to the fact that the arcuate sections 5 of the outer ring andthe arcuate sections 11 of the inner ring are under the action of thetension elements 10, it is guaranteed that the rings 3, 9 are supportedon the hub 1 in a suitable manner by means of the pressure elements 6and the tension elements 7, 14. In the case of the embodiment shown inFIG. 4, the tension elements 7, 14 are provided with such a structuraldesign that they have their respective ends secured to a carrier 13 andthat they are deflected round the deflection roller 17 in the area ofthe hub. In the embodiment according to FIG. 4, which shows a front viewof the rotor, two tension elements 7, 14 or only one tension element 7may be used in analogy with the embodiment according to FIG. 1 to 3.

For the sake of clarity, each of FIG. 1 to 4 only shows a subarea of therotor according to the invention. It goes without saying that several,at least three, tension elements 6 as well as a corresponding number oftension elements 7, 14 must be provided round the rotational axis of thehub 1 so as to guarantee sufficient stability of the rotor. Preferably,there are provided six or twelve such arrangements of pressure elements6 and tension elements 7, 14. In the case of the embodiments shown, thenumber of deflection rollers 8 as well as of the arcuate sections 5 ofthe outer ring and of the arcuate sections 11 of the inner ring as wellas the number of rotor blades 4 correspond in an analogous manner to thenumber of arrangements of pressure elements 6 and tension elements 7,14.

FIG. 5 shows an additional possibility of designing the hub 1 as well asthe pressure elements 6 and the tension elements 7, 14. In analogy withthe embodiment shown in FIG. 1, the deflection roller 17 for the tensionelement 14 is arranged on the hub 1, whereas the deflection roller 17for the tension element 7 is secured by means of a carrier 19 at aradial distance from the hub 1. The two deflection rollers 17 arecoupled by means of a strut 20. In the case of this embodiment, thetension elements 7, 14 approximately have the same length.

A characteristic property of the disclosed embodiments of the rotoraccording to the invention is that their mass is particularly small,whereby the resultant gyroscopic effects can also be restricted tocorrespondingly small values. Furthermore, the axial bearing means 2 isfreely accessible so that it is possible to support the rotor in anappropriate manner in such a way that the still existing gyroscopiceffects contribute to the stabilization of said rotor. Such a support ofthe rotor can be achieved e.g. by means of a cardanic suspension.Furthermore, it is possible to provide different numbers of rotor blades4 and arrangements of pressure elements 6 as well as of tension elements7, 14, for example six arrangements of pressure elements 6 and tensionelements 7, 14 and twelve rotor blades 4.

I claim:
 1. A rotor for a wind driven generator comprising:(a) a carriermember; (b) an axial bearing means disposed on the carrier member; (c) ahub disposed on the carrier member adjacent to and rotatably supportedby the bearing means; (d) the hub includes:i. a first flange disposed ator near the end of the hub nearest the bearing means; ii. a secondflange disposed at or near the other end of the hub; and iii. a thirdflange disposed between the first and second flanges; (e) a plurality ofpressure elements mounted to and extending outwardly from the thirdflange and angled towards the bearing means; (f) an inner ringcomprising a plurality of first arcuate sections disposed in essentiallythe same rotational plane as the bearing means and supported by andmounted to the pressure elements; (g) an outer ring comprising aplurality of second arcuate sections disposed in essentially the samerotational plane as the bearing means and outside of the inner ringwhere one second arcuate section corresponds to each first arcuatesection; (h) a plurality of blades disposed where one blade is disposedbetween each first arcuate section and corresponding second arcuatesection; (i) a plurality of first deflectors where one first deflectoris disposed inside each first arcuate section perpendicular to thelongitudinal axis of the carrier; (j) a plurality of second deflectorswhere one second deflector is disposed in each second arcuate sectionsubstantially parallel to the longitudinal axis of the carrier; (k) aplurality of third deflectors where one third deflector is disposed ineach first arcuate parallel to the first deflector disposed in the samefirst arcuate section; (l) a plurality of flexible first tensionelements where each first tension element:i. is connected at one end toa pressure element; ii. disposed in sliding relation in the secondflange; iii. disposed against a first deflector means in slidingrelation; iv. disposed against a second deflector means in slidingrelation; v. connected at the other end to a second deflector meansdisposed in an adjacent second arcuate section (m) a plurality of secondtension elements where each second tension element means is:i. connectedat one end to a pressure element; ii. disposed in sliding relation inthe first flange; iii. disposed against a third deflector in slidingrelation; iv. disposed against a second deflector in sliding relation;v. connected at the other end to a second deflector disposed in anadjacent second arcuate section to circumferentially support the outerring.
 2. A rotor comprising:a. a carrier; b. a bearing disposed aroundthe carrier; c. a hub disposed around the carrier adjacent to thebearing; d. the hub comprises:i. a first end disposed adjacent to thebearing; and ii. a second end disposed opposite the bearing end; e. aplurality of first arcuate sections that define an outer ring; f. aplurality of second arcuate sections that define an inner ring; g. theinner ring and the outer ring are disposed in substantially the sameaxial plane as the bearing means; h. a plurality of blades disposedbetween the inner ring and the outer ring; i. a first deflector meanscentrally disposed in each first arcuate section substantially parallelto the longitudinal axis of the hub; j. a second deflector meansdisposed in each second arcuate section substantially perpendicular tothe longitudinal axis of the hub; k. a third deflector means disposed ineach second arcuate section substantially parallel to the seconddeflector means; l. a pressure element disposed between each secondarcuate section and the hub; m. a plurality of flexible first tensionelements; n. each flexible first tension element is:i. attached at oneand to a pressure element; ii. connected in sliding relation to thesecond end of the hub; iii. disposed against a second deflector means insliding relation; iv. disposed against a first deflector means insliding relation; and v. connected at its other end to a first deflectormeans disposed in an adjacent first arcuate section; o. a plurality offlexible second tension means; p. each second tension means is:i.attached at one end to a pressure element; ii. connected to the firstend of the hub in sliding relation; iii. disposed against a thirddeflector means in sliding relation; iv. disposed against a firstdeflector means in sliding relation; and v. connected at its other endto a first deflector means disposed in an adjacent first arcuatesection.
 3. A rotor according to claim 2 where the first and secondtension elements comprise flexible wire ropes.
 4. A rotor according toclaim 2 where the first and second arcuate sections are composed of aplastic material.
 5. A rotor according to claim 2 further comprising:a.an adjustment means disposed between the first tension element and thepressure element; and b. an adjustment means disposed between the secondtension element and the pressure element.